The present invention relates to apparatus for extracting energy from the wind. More particularly, the present invention is concerned with improvements in apparatus which utilizes a sail or wing which may be buoyant in its own right or which may be carried aloft by the configuration of the sail. The sail is designed to be carried to a relatively high altitude of several hundred feet above the surface of the earth where the wind velocity is considerably greater than close to the surface and consequently the wind's energy density is higher. The wings are disposed at the end of a tethered line for the power transmission and/or for controlling the orientation and relative position of the sails. Such apparatus does not require the use of a mast or large supporting tower as is the case with most propeller type windmills.
Apparatus of the general type described above is disclosed and claimed in my U.S. Pat. No. 3,924,827 issued Dec. 9, 1975. The present invention relates to improvements in the basic invention covered by my patent.
My patented invention employs a series of sails which may be comprised of a hollow buoyant body filled with a lighter than air gas. The buoyant sail has a concave surface facing the incoming wind and is designed to lift with it the necessary tether line leading from the body to the ground level structure which might include an electric generator. The sails are employed in series with the sails alternately being played out under the influence of the wind and then drawn back while presenting a smaller effective surface to the wind. The tether and/or power transmission lines may be attached at their lower end to pulleys which through suitable shaft and gear arrangements are connected to appropriate energy utilization equipment such as an electrical generator. Control means are employed to automatically reverse the direction of movement of the wings both when the line is played out and when the line is retracted to a predetermined point. The wing may be filled with a lighter than air gas such as hydrogen or helium. The sail includes means to add or subtract the gas, for example, to make up for losses, to compensate for changes in atmospheric pressure, which would change the volume of the filler gas and therefore effect the sail's lifting capacity, to compensate in changes in volume of the gas due to changes in atmospheric temperature, and to make certain that the internal pressure of the filler gas is greater by a certain amount than the atmospheric pressure. Changes in the amount of filler gas may also result in changes in the height of the wing.